P0172 error code

[Gleplae]

hi I have a 2006 Toyota Corolla which is giving me a check engine light error code p1072. About 2 month ago the car had a p1071 error code, indicating fuel mixture was too lean. I researched on line and proceed to inspect the vehicle for a vacuum leak and did not see any obvious problems. I cleaned the throttle body and then replaced the maf sensor. Once I replaced the maf sensor the error code disappeared. But now I am getting a p1072 error code which suggests that the fuel mixture is too rich. The car runs fine except for some rough idle issues when car is first started in subzero weather otherwise when the engine has warmed up it runs fine.

[oldcodger]

P172 does seem to be very similar in the action required as for P171 but my lookup book shows that P172 could also be down to fuel line/pressure problems.

 

[Red_Corolla]

I think the most important starting point is to check that the replacement MAF sensor is genuine Denso or whatever Toyota fitted to the car originally. I say that because aftermarket MAF sensors are notoriously unreliable, they cost half the price but simply don't work properly. I had a MAF failure on my Volvo years ago and opted for a cheaper £100 sensor from Eurocarparts. It cleared the fault but also reduced the car's power an enormous amount. I had to spend twice as much on a genuine Bosch sensor to get things back to normal.

To diagnose a fuel mixture fault properly, it really requires a diagnostic tool that can show live data such as fuel trim figures, O2 sensor reading etc.